The invention relates to catalysts, a method of producing the catalysts and a process using the catalysts. In another aspect the invention relates to a particularly effective ethylene polymerization catalyst and process.
In the production of polyolefins, such as for example polyethylene, polypropylene, ethylene-butene copolymers etc., an important aspect of the various processes and catalysts used to produce such polymers is the productivity. By productivity is meant the amount or yield of solid polymer that is obtained by employing a given quantity of catalyst. If the productivity is high enough then the amount of catalyst residues contained in the polymer is low enough that the presence of the catalyst residues does not significantly affect the properties of the polymer and the polymer does not require additional processing to remove the catalyst residues. As those skilled in the art are aware, removal of catalyst residues from polymer is an expensive process and it is very desirable to employ a catalyst which provides sufficient productivity so that catalyst residue removal is not necessary.
In addition to productivity of a catalyst, another important aspect of a process and a catalyst is the properties of the polymer particles. It is desirable to produce polymer particles which are characterized by strength, uniformity of size, and relatively low fines. Although polymer fluff having relatively high percentages of fines can be handled with plant modifications, a polymer of high productivity and low fines is highly desirable.
Accordingly, an object of the invention is a catalyst.
Another object of the invention is a polymerization process for using the catalyst capable of providing excellent polymer productivities as compared to prior art catalysts.
Another object of the invention is a catalyst and a polymerization process in which the polymer produced contains catalyst residues in an amount so that catalyst residue removal is unnecessary.
Another object is a catalyst characterized by high productivity and low fines.
Another object is a polymerization process for using the catalyst capable of providing improved polymer productivities with low fines.
The invention can be understood by reference to the following description.